Conventionally, in response to worldwide increase in the production of bale rubber complying with international standards, transporting form thereof has changed to bulk handling. In the early years of synthetic rubber production, synthetic rubber that has been compressed and molded into a bale with a press was piled high after being wrapped with a thin, low melting point polyethylene film. In such a case, due to the pressure caused by high piling, deformation called cold flow occurred at the lower portion of the bale rubber, and since the polyethylene film was torn due to the deformation and since the rubber stuck out, there were cases in which the bale rubber was transported while being packed in a three plied kraft paper sack having strength to prevent tear; however, since the raw synthetic rubber was stacked on a pallet in multilayers amounting to over a ton, the bale rubber at the lower portion was deformed due to weight-induced pressure from above and, accordingly, the bale rubber tore out of the paper sack and exposed itself and, in the end, the stacked and piled state was torn down making transportation difficult. Accordingly, a strong kraft paper sack was in demand.
However, especially during long-distance transportation in the summer season, deformation due to cold flow occurred frequently making it most difficult to wipe out paper sack tearing incidents; accordingly, wooden framed box-shaped pallet was put into practical use. However, due to measures against wasteful use of wood resource and due to problems of foreign matters such as wood chips getting mixed, the packaging form has further been changed to stacking and piling the bale rubber, which has been wrapped by film without any paper sack packaging, inside a recoverable and reusable box-shaped metal pallet. Furthermore, in recent years, it has become typical to internationally distribute the bale rubber accommodated inside a knock-down box-shaped pallet formed of thin steel plates.
The boxed-shaped metal pallet accommodates 30 pieces of 35 kg bale rubber (about one ton), and in rubber processing factories, stacking and storing three box-shaped pallets are normally the case and the box-shaped pallets are designed for such storing; however, when even a single side plate of the pallet is removed, the strength for stacking and storing is lost. Moreover, when the bale rubber is unloaded from the box-shaped pallet for cutting and weighing, in order to simplify work, the plate on the lateral side of the box-shaped pallet is dismounted to unload the bale rubber.
However, as regards the pallet in which one side plate has been removed, it is difficult to return the removed plate and reuse the box-shaped pallet. In other words, when one side plate of the box-shaped pallet is removed, the bale rubber at the lower portion that has been accumulating the weight-induced pressure from the bale rubber at the upper portion until then instantaneously tears the thin polyethylene film packaging and starts to swell; accordingly, the box-shaped pallet that is a knock-down type structured so that the side plates are inserted thereto cannot reset the dismounted plate as long as there is bale rubber inside. As a result, the box-shaped pallet that has been stacked in three layers loses its strength that allowed staking to be performed in multilayers, thus, leaving no other way of storage but to place the pallet flat in a single layer and, thus, requiring a large storage space.
Since there are such problems, there is an earnest demand in rubber processing factories to unload the bale rubber from the box-shaped pallet without dismantling the box-shaped pallet. Regarding the work of taking the 35 kg bale rubber out, if it is continuous work, even just putting the bale rubber on a conveyer from a flat pallet becomes hard work and many lower back disorders are induced. Labor law restricts working environments in which a heavy load of 20 kg or more is continuously carried by man and, furthermore, although a synthesis resin manufacturer is on the way to commercializing a bale-shape that is a 35 kg bale cut into half, it has been evaluated that it is not suitable for transportation since it lacks stability during stacking. In such a case, by halving the formed thickness dimension of the bale rubber, the stacking stability is resolved; however, the production capacity of the synthetic rubber manufacturing process is reduced by half and it is inevitable that a large amount of investment is needed in reorganizing the manufacturing process; accordingly, the above cannot be achieved easily. The above state is the reason why rubber processing factories are waiting for a simple device that can handle bale rubber to be put into practical use.
The following are labor-saving machinery that are the kind of labor-saving machinery for work described above that has been put into practical use until now.
First, in a gripping tool made of steel called “ice gripper” that has a general structure, when two gripping arms that have two internally oriented claws that face each other at the distal ends and that are rotatably attached while being intersected at a fulcrum are lifted by being suspended with a chain or wire, the two claws at the distal ends of the intersecting two gripping arms grip and hang the ice or the like facilitating lateral movement. “Ice grippers” that are used to handle bale rubber are known.
However, since the above-described “ice gripper” needs to pinch the opposing lateral surfaces of the bale rubber with large gripping arms, in order to have the gripping arms interpose between the appressed bale rubber inside the box-shaped pallet, work such as tearing the bale rubber apart with a hook so as to provide vacant spaces allowing the gripping arms to enter is indispensable. Furthermore, since the hanging mechanism needs to be wire or a chain that has flexibility, when moved laterally while being hung, the bale rubber with weight becomes a pendulum and swings; accordingly, it is unstable and effort and skill are required in maintaining the bale rubber and in handling the operation switch of the hoist.
Furthermore, as described above, when the bale rubber is wrapped in polyethylene film and is accommodated inside the box-shaped pallet, even though through the film, the bales are appressed to each other and deformation of the bale rubber cannot be totally avoided; accordingly, it is not possible to unload the bale with the force of the vacuum suction pad of the vacuum suction type lifter that has been in practical use as before and unloading work is carried out by removing the side plate of the box-shaped pallet. Particularly, in rubber factories for industrial products that process a variety of types of bale rubber, such as automobile parts, a tool that allows the bale rubber to be unloaded without dismantling the box-shaped pallet is awaited for from an aspect of the storage area.
Furthermore, there is a device having a weight balance function including a vacuum suction type hand portion in which lifting/lowering and horizontal movement can be performed freely. The above is a device that can easily lift bale rubber with the weight balance function by, while the operator holds on to the operation handle equipped on the hand portion, operating an operation element for vacuum action while having a large suction pad abut against the center of the surface of the bale rubber and by attracting the bale rubber to the suction pad. Although the above devices have been put into practical use, because satisfactory unloading of the bale rubber is not necessarily achieved as described below, appearance of a user-friendly device is awaited.
The inconvenience of the “ice gripper” is resolved in the above-described device provided with the vacuum suction type handle portion. In particular, it is advantageous in that there is a suction operation element on the operation handle of the suction pad that constitutes the hand portion and that suction can be performed before lifting the bale rubber with the handle. Regarding the lifting of the bale rubber, since the hand portion is mounted on the arm of a vertically and horizontally moving device having a weight balance structure, stability in maintaining spatial position is good and the lifting force required may be one that is enough to guide the lifting/lowering. However, there is a serious weakness in that when the surface of the bale rubber is not smooth, degree of vacuum that supports the weight cannot be maintained and the bale rubber cannot be lifted. When the thin polyethylene film is absorbed and when the film is detached from the surface of the bale rubber, the film becomes torn and the bale rubber drops off. Furthermore, when the bale rubber are appressed to each other inside the box-shaped pallet, lifting power becomes insufficient and lifting cannot be performed unless the appressed bale rubber are torn apart from each other with a hook. The side plates around the box-shaped pallet is roughly 1.2 m, and after unloading 10 bales, unless a side plate on one side of the knock-down box-shaped pallet is removed, the suction pad of the hand portion cannot reach the bale rubber and suction operation cannot be carried out. Accordingly, in any case, in existing devices, there is difficulty in unloading the bale rubber inside the box-shaped pallet without dismantling the box-shaped pallet.